When you started your tax return Turbo Tax assumed you did not get any stimulus checks so it gives you the full 1800 stimulus as a refund on your tax return. Then at the end you enter you already got the 1800 so it takes it out of your refund. Because you already got it. You don't get it twice. Or if you only got the first 1200 you still get the second 600. Check 1040 line 30 for any amounts you didn't get during the year.
